#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;

class Solution
{
public:
    vector<vector<int>> matrixBlockSum(vector<vector<int>>& mat, int k)
    {
        int m = mat.size(), n = mat[0].size();
        vector<vector<int>> dp(m+1, vector<int>(n+1));
        for(int i=1; i<=m; i++)
            for(int j=1; j<=n; j++)
                dp[i][j] = dp[i-1][j]+dp[i][j-1]-dp[i-1][j-1]+mat[i-1][j-1];

        vector<vector<int>> answer(m, vector<int>(n));
        for(int i=0; i<m; i++)
        {
            for(int j=0; j<n; j++)
            {
                int x1 = max(0, i-k)+1, y1 = max(0, j-k)+1;
                int x2 = min(m-1, i+k)+1, y2 = min(n-1, j+k)+1;
                answer[i][j] = dp[x2][y2]-dp[x1-1][y2]-dp[x2][y1-1]+dp[x1-1][y1-1];
            }
        }
        return answer;
    }
};
